FILEREADER AND FILEWRITER IN JAVA

These two classes are used to read and write data from a file as characters. It is recommended to use FileReader and FileWriter classes to read data from text file where as FileInputStream and FileOutputStream classes are only recommended to read and write image files.

FileReader –

Constructors of FileReader  –

1. FileReader(String name)

2. FileReader(File f)

Methods of FileReader –

1. int read() – It attempts to read next character from the file and returns its Unicode value. If the next character isn’t available, then we will get -1 i.e., it returns -1.

2. int read(char[] ch) – It attempts to read enough characters from the file into the char[] array and returns the number of characters copied.

3. void close()

Example –

import java.io.File;

import java.io.FileReader;

import java.io.IOException;

public class Read1 {

          public static void main(String[] args) throws IOException{

                   File f = new File("xyz.txt");

                   FileReader fr = new FileReader(f);

                   char[] ch = new char[(int)f.length()];

                   fr.read(ch);

                   for(char ch1:ch)

                   {

                             System.out.print(ch1);

                   }

                   fr.close();                     

          }

}

Output –

i love coding

i love java

i am a hacker

FileWriter-

Constructors of FileWriter –

1. FileWriter(String s)

2. FileWriter(String name,boolean append)

3. FileWriter(File f,boolean append)

Methods of FileWriter –

1. write(int i) – To write a single character to the file.

2. write(char[] ch) – To write an array of character to the file.

3. write(String s) – To write a string to the file

4. flush() – To give guarantee that the last character of the data is added to the file.

5. close() – close the file.

Example –

import java.io.FileWriter;

import java.io.IOException;

public class Read1 {

          public static void main(String[] args) throws IOException{

                   FileWriter fw = new FileWriter("xyz.txt");

                   fw.write("Welcome to Coding makes perfect");

                   fw.write("\n");

                   fw.write("Lets code");

                   fw.write("\n");

                   fw.write("Guwahati");

                   fw.write("\n");

                   char ch[] = {'A','S','S','A','M'};

                   fw.write(ch);

                   fw.flush();

                   fw.close();

                   System.out.println("Data succesfully written into the file");

          }

}

Output –

Data succesfully written into the file

Limitations with FileReader and FileWriter –

While writing data by using FileWriter, we have to insert separator(mandatory) which is valid from OutputStream to OutputStream, hence it is overhead to the programmer. While reading the data by using FileReader we have to read character by character which isn’t convenient to the programmer and it isn’t recommended with respect to performance. To overcome these problems we should go for BufferedWriter and BufferedReader.